The following statement,
therefore, by Sir S. Baker[34] is inexplicable, namely, that a rhinoceros,
which he shot in North Africa, "had no ears; they had been bitten
off close to the head by another of the same species while fighting;
and this mutilation is by no means uncommon."

Lastly, with respect to monkeys. Some kinds, which have moveable ears,
and which fight with their teeth--for instance the _Cereopithecus ruber_--
draw back their ears when irritated just like dogs; and they then have
a very spiteful appearance. Other kinds, as the _Inuus ecaudatus_,
apparently do not thus act. Again, other kinds--and this is a great anomaly
in comparison with most other animals--retract their ears, show their teeth,
and jabber, when they are pleased by being caressed. I observed this
in two or three species of Macacus, and in the _Cynopithecus niger_.
This expression, owing to our familiarity with dogs, would never be
recognized as one of joy or pleasure by those unacquainted with monkeys.

[34] `The Nile Tributaries of Abyssinia,' 1867, p. 443.

_Erection of the Ears_.--This movement requires hardly any notice.
All animals which have the power of freely moving their ears,
when they are startled, or when they closely observe any object,
direct their ears to the point towards which they are looking,
in order to hear any sound from this quarter. At the same time
they generally raise their heads, as all their organs of sense
are there situated, and some of the smaller animals rise on their
hind-legs. Even those kinds which squat on the ground or instantly
flee away to avoid danger, generally act momentarily in this manner,
in order to ascertain the source and nature of the danger.
The head being raised, with erected ears and eyes directed forwards,
gives an unmistakable expression of close attention to any animal.
CHAPTER V.

SPECIAL EXPRESSIONS OF ANIMALS.

The Dog, various expressive movements of--Cats--Horses--Ruminants--Monkeys,
their expression of joy and affection--Of pain--Anger--Astonishment
and Terror.

_The Dog_.--I have already described (figs. 5 and 1) the appearance
of a dog approaching another dog with hostile intentions,
namely, with erected ears, eyes intently directed forwards,
hair on the neck and back bristling, gait remarkably stiff,
with the tail upright and rigid. So familiar is this appearance
to us, that an angry man is sometimes said "to have his back up."
Of the above points, the stiff gait and upright tail alone
require further discussion. Sir C. Bell remarks[1] that,
when a tiger or wolf is struck by its keeper and is suddenly
roused to ferocity, every muscle is in tension, and the limbs
are in an attitude of strained exertion, prepared to spring.
This tension of the muscles and consequent stiff gait may be
accounted for on the principle of associated habit, for anger
has continually led to fierce struggles, and consequently
to all the muscles of the body having been violently exerted.
There is also reason to suspect that the muscular
system requires some short preparation, or some degree
of innervation, before being brought into strong action.
My own sensations lead me to this inference; but I cannot
discover that it is a conclusion admitted by physiologists.
Sir J. Paget, however, informs me that when muscles are suddenly
contracted with the greatest force, without any preparation,
they are liable to be ruptured, as when a man slips unexpectedly;
but that this rarely occurs when an action, however violent,
is deliberately performed.

[1] `The Anatomy of Expression,' 1844, p. 190.

With respect to the upright position of the tail, it seems to depend
(but whether this is really the case I know not) on the elevator muscles
being more powerful than the depressors, so that when all the muscles of
the hinder part of the body are in a state of tension, the tail is raised.
A dog in cheerful spirits, and trotting before his master with high,
elastic steps, generally carries his tail aloft, though it is not held
nearly so stiffly as when he is angered.